The present invention relates generally to improvements in air-conditioning systems wherein a central supply of cool air and at least one distribution unit is provided for each room or volume to be air-conditioned. More particularly, this invention relates to a new and improved air-conditioning system wherein a distribution unit regulates the temperature in a room by selectively controlling the amount of: (1) cool air supplied to the room (2) recirculated air supplied to the room and (3) heating of the air supplied to the room. To accomplish this the present invention utilizes an improved distribution unit which has a blower and heating unit therein which cooperates with a controlled inlet damper and a barometric recirculation damper.
In the air-conditioning and heating of large buildings having a plurality of separate rooms or spaces therein, it has been a general practice to utilize a central air-conditioning system which supplies preconditioned air to each of the rooms or spaces. It has also become a common practice to utilize building construction methods which incorporate a larger amount of glass or other materials on the exterior which have poor thermal insulation properties. Due to the use of these materials with poor thermal insulation properties, the air-conditioning requirements of the different rooms or spaces in the building can vary substantially due to the incidence of sun, wind or other temperature variation sources on one or more of the sides of the building. In addition, for purposes of economy it has been common to deactivate the central air-conditioning system during the night or at times when the building is not in use, thus necessitating that the building during much of the year be heated in the morning prior to the building's use.
Although prior air-conditioning systems which utilize a central unit have served their purpose, they have not proved entirely satisfactory under all conditions of service for the reason that considerable difficulty has been experienced in independently controlling the temperature in various rooms or spaces of the building with different heating and cooling requirements. In addition, during the warm-up in the mornings, it is necessary to operate the complete system, thus adding to the costs of operating the system.